I'm ditto-ing Paul on this one. Let's face it, the US is a huge country.
I grew up overseas and only moved here for the university, and the in-your-face patriotism really startled me at first. True, the Brits and the French will criticise their governments--but, on the other hand, their governments have existed for a LONG time. The US is much younger, its "independence" much newer and generally, it's just young. Canada is a somewhat different case since it was a protectorate of the British Empire and therefore grew up under its wing.
In part, I think US citizens are so patriotic because they KNOW they have a huge role in the world. When you can go anywhere overseas and see your president on the news nightly, you might fall victim to a superiority complex.
Also, I think it might be fair to say that many US citizens feel attacked in debates on politics, especially when they are in groups of "foreigners". I know I do as one of the only North Americans in my program. I often find myself the hapless victim of random conversations wherein people throw national policy at me as if I invented it. I notice they take a different tone with people from other countries, but with me they just assume that I am propriatorially responsible for any and all actions by the government. This makes me a whole lot more defensive than I ever was before!
